High vacuum pump apparatus



pi. 17,1949. H 1. STOLTZ HIGH VACUUM PUMP APPARATUS e Sheets-Sheet 1 Filed May 6, 1958 Sept. 1?, 194%. H. LSTOLTZ HIGH VACUUM PUMP APPARATUS 6 Sheets-Sheet 2 Filed May 6, 1958 w b wv Km J H. 5, w M\ w i m. Q 1! \Q%% P 17. 1940. HL'LSTOLTZ HIGH VACUUM PUMP APPARATUS 6 Sheets-Sheet 3 Filed May 6', 1938 p H. 1. STOLTZ 2,215,256

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ATTORNEYS.

Patented Sept. 17,1940 7 UNITED STATES 7 2,215,25 5 man VACUUM'PUMP APPARATUS.

Harold I. Stoltz, Hyde Park, Masa, assignor to Kinney Manufacturing Company, Jamaica. Plain, Masa, a corporation of Massachusetts Application May 6, 1988, Serial No. 206,423 I 11 Claims. (Cl. 230--147) In the commercial development of high vacua.

' in the manufacture of radio tubes, light bulbs and like envelopes or vessels, increasing demands have grown as the manufacturers of such articles '6 have seen new possibilities could their equipment be raised to super efliciencies.

"Originally a high vacuum by means of an oil sealed vacuum pump was thought of as anything 'over 29 inches of mercury, as read on one of the 10 old gages. Researches at that time had developed vacua. only readable on supersensitlve instruments like the so-called McLeod gages which provided readings in microns. These were supposed, with some refinements given them during my earlier researches, to represent the limit of measurement of degrees -of exhaustion then known outside of laboratory rareficaticns.

That such rarefications could be developed and held in operative subservience to manufactura ing manipulations, steps and production processes,

was considered not humanly possible in any engineering sense. According to my present concept I have improved my systems and secured an embodiment that shows on my adapted McLeod 25 gages a rarefication beyond what it was devised to indicate. In checking my system on the basis of laboratory gages, using an emanation extension on a radio active source, I found that I-was attaining practical vacua. readings in hundredths' so of a micron, This,.it will be understood by those familiar with laboratory experiments, represents measurement so delicate as to create new standards in the field of production of such practical importance as hardly at once to be fully apsg preciated.

- During the past few'years it has been evident that the radio tube industry desired pumping equipment capable of producing a lower absolute pressure with speed and reliability consistent with that obtained with available high vacuum pumps now in general use throughout the industry.

Various types of equipment are being used, but with only partial success. During this period many experiments have been made with the 4g pump of patent to Kinney, No.. 1,623,315 which ultimately led to-the present invention.

In studying the performance of my experimental units, it was apparent that there were too many threaded and other connections to 50 expect to produce commercially units which would approach anywhere near the actual capacities required. Further,-when Istudied the natural entrainment of air in oil it became an apparent fact that the oil supply entering the high vacuum stage 55 must be completely deaerated; By my research I definitely proved that if a supply of deaerated 011 between the high and low vacuum stages were to be maintained, the pressure differential was insuificient to provide a consistent flow of sealing oil to the high vacuum stage. It will be under- 5 stood that the problem is tomaintain at all times a sufflcient amount of sealing oil about all the joints and parts of the pump so that there will be no loss of the high vacuum resulting from the evacuating action of the pump.

In general, my concept. contemplated oil sealed mechanical pumps in which I would stage two pumps in one casing and provide the stages with a positive seal, one from the other, except through the ported connections provided for communication one to the other. Also, I would provide sealing oil free from air or vapor for the high vacuumv stage which would be independent of the oil seal of the backing-upstage, and which 011 would be located intermediate the two stages and continugo ously deaerated by the suction of the backing up stage to which the body of oil would be subjected through the ported connections between the two stages. I would also provide a positive means of supplying this deaerated sealing oil to the high 5 vacuum stage in proper regulated-quantity as a definite seal to the working vacua. By staging in one casing, I would reduce the number. of joints which must be sealed oil to prevent air leakage into the pump to a minimum, this being particuan larly important on the high vacuum stage.

For the purposes of illustration of a subject matter so subtle I am compelled to disclose my own practical structural basis of operation. Because my structure is capable of a wide range of modification, its tolerances being so fine and so difiicult accurately to keep checked, I make such detailed disclosure relying on securing adequate patent coverage to protect me against close competition. 40

In the drawings I have shown a unit of obvious 1 adaptability, and to those skilled in the art, of great efiiciency. Apart from my method which it operatively epitomizes, it represents a novel pumping device of mechanical merit which embodies various features of advantage.

Throughout the specification and drawings like reference numerals are employed to indicate corresponding partaand in the drawings;

Fig. 1 indicates a central vertical section through a unit according to my invention.

Fig; 2 illustrates a transverse section through the left or high vacuum side of the unit of Fig.- 1.

Fig. 3 is a similar section through the backingup section to the right of Fig. 1.

system according to my invention operating in' conjunction with a tube machine arbitrarily indicated as of a rotary table type, and

Fig. 9 is a section on the lines 3--9 of Figs. 1 and 3.

In the illustrative embodiment shown in the drawings, I have indicated at I a unit casing having its high vacuum side indicated at 30 and its backing-up stage indicated at 20. The casing I is partially divided midway of its length by a partition or central wall I isolating atmospherically two independent but cooperative sections indicated as 2| and 3|. On each side of the wall I is one of my oil seal pump units 2 (see Figs. 2 and 3).

The casing I also, includes a compartment 3 forwardly or rearwardly of the pump units 2. which compartment may be of the overhanging construction shown in Figs. 2 and 3 or of other 30 design. This compartment also is divided substantially midway as by the wall I0a which is connected to the wall I0 except adjacent the top of the casing as at the point marked P in Figs. 2 and 5.

0n the left hand side of this partition I0a. as

shown in Figs. .and 9, I provide an oil chamber I30 intermediate of the two pump sections 30 and into which is delivered the exhaust from theport I0 of the high vacuum side of the compound pump. From this chamber I leads the corridor P (Fig. 5) through which the exhaust oil and gases are drawn by suction to the intake chamber 2| of the backing up pump section 20. As this chamber I30 is open to the intake or suction side 2| of the pump section 20, the oil 0 therein continuously is being deaerated, a vacuum in the vicinity of a few microns being maintained.

A supply of such deaerated oil 0 is maintained in this intermediate oil chamber I30 at a level Just below the mouth of the'exhaust I0 (Fig. 2). Thus the two pumping stages are completely sealed one from the other except through the corridor P. The deaerated oil 0 is positively fed to the oil sealing system of the pump 30 as hereinafter described.

The chamber I20 on the opposite side of the wall I00 adjacent the second stage pump 23 serves as a reservoir for the oil under atmospheric pressure which supplies the oil seal for the second stage pump20.

The central wall I0 has in its thicker portion I0 recesses for the cylindrical sides of the slide pins 5 in which the hollow stems I of the rotary piston 3 are guided. (Fig. l). The piston 3 sweeps the cylindric interior 9 of the lower part of the casing I on each side of its central wall l0. The hollow stems 'I have ports 0 which are.

This is tightly packed in the wall III as at II to prevent any leakage between the sections 3| and aaiaase 3|. Theshaft 4 is supported in oil sealed bearings 4I and ii mountedwithin pockets 42 and 02 in the heads and respectively, the sealing control of which will be discussed later.

On the head 50 is mounted a gear pump in which are sealed a pair of continuously driven intermeshing gear pump rotors GI and 62. The

- rotor gear ii is fast asat il to a short shaft 33 which has a key and kerf driving connection with the outer end of the main drive shaft 4 (Fig. 1).

This short gear shaft 63 is mounted in a plate 34 having a recessed face disposed next to the bearing 5| so as to close the shallow annular oil'chamber 52 containing the bearing 5|.

The oil pump 80 communicates with the de-. aerated oil reservoir I30. It comprises the casing 80 (Figs. 6 and 9), suitably bored longitudinally to provide the passageway .31 for the deaerated oil to the pump rotors SI, 62, this passage 31 communicating with a passage 31' through the wall of the main casing -I leading from the reservoir I33 (Fig. 5). Spaced laterally and angularly from the inlet passage 01 is the by-pass or return passage 60 leading from the discharge side of the oil pump 30 and which communicates with a passage 83' through the casing wall communicating with the reservoir I33. In this by-pass is positionedan adjustable needle valve 33 for regulating the flow of sealing oil to the high vacuum pump 30 through the passage 64' in the plate 64. A spring loaded ball valve 10 (Figs. 6 and 9) which permits the return of surplus oil to the reservoir only when the desired pressure within the pump 30 is exceeded is also positioned in the by-pass 33.,

The deaerated oil is forced by the pump 33 to the bearing chamber 52 as indicated above by way of the transverse passage 34' through the plate 34 (Figs. 1 and 9), from which chamber the sealing oil passes to the usual oil sealing system of the high vacuum pump 30 along the shaft 4 which communicates with'the various sealing oil ducts and grooves about the parts 5, 3, I, 3 and 9, for example as shown in the patent to Kinney 1,623,315. The pressure maintained in the chamber 32 is sufhcient to keep the oil sealing system full of sealing oil at all times and ltlo promptly replace any withdrawn with the exaust. I

The pump casing 33 is suitably fastened to the head 50 as by bolts I3, the head 50 being secured to the main casing I as by bolts 14.

Opposite the gear pump 63 on the other end of the casing I is mounted what may be called the open head cap 30. in which the shaft 4 is sealed against oil leakage as at 3|. This head cap backs up an inner open head cap 34, having a concaved face 35 disposed next to the bearing 4| opposite the concavity 13 so as to form the annular oil sealing chamber 43.

Through the head 43 is guided the oil 0' from the reservoir I30 to the oil sealing system of the backing up pump section 23, the oil being fed to the sealing system of this pump only under atmospheric pressure regulated by the adiustable needle valve 31 in the passage 30. Such pressure causes the sealing oil to flow to an extent adequate to protect the vacuum in this open head pump, the function of which is to back up the more complete rarincation secured with the pump 33. The oil passage 33' through the head 43 and cap 33 (Figs. 7 and 9) communicates with the passage 33 through the casing I to the reservoir I33 (Figs. 5 and 9) The passages 33-33 deliver oil under atmospheric pressure to the chamber 42 in which a supply of oil builds up for the oil sealing system of the backing-up pump 20, whichoil passes from the chamber 42 along the shaft 4 to the usual oil sealing grooves of the pump parts. The passages 86-88 also supply 011 for sealing and lubrication to the rotary seal in the chamber 80 of the cap 80.

As the chamber 42 is emptied by oil passing therefrom to the oil sealing system as required, the valve 8! is adjusted to permit oil from the reservoir I20 to enter the chamber 42 in proper quantity. The oil seal of the unit is along the general lines heretofore established, but under my novel control it becomes a new system.

In the first place, it must be explained that in my research I have discovered what I believe is the-missing linkage between the surprisingly high vacuums as already demonstrated, and the supposedly impossible super-vacua for which commercial science has been waiting.- This it the intake chamber 3| of the high vacuum phase.

will be seen results from the continuous supply of deaerated sealing oil, to replace that withdrawn in the exhaust,- from an independentcontinuously deaerated oil source, wherever located, connected intermediate the auxiliary systems, identified as the oil reserve 0' in Fig. 2. This source is independent of and to be distinguished from the secondary oil reserve 0' on what I have termed the open or backing-up side of the unit on the opposite side of the partitions I0 and I0a.

In my oil seal system as developed by me I have introduced this novel concept of a final oil barrier of deaerated oil protective of the high vacua developed. As, shown, this is accomplished simply and effectively by the positive needle valve control 69 which, with its companion check valve 10, ensures the definite feed of deaerated oil to seal the parts in predetermined feed (Fig. 6).

As first suggested, the demands of industry kept close on the heels of such improvements as pump manufacturers had been able to make. The production of radio'tubes is a striking instance of the demand or challenge and the mechanical diificulties entailed by its established machinery and practice.

As illustrative of a hookup in which a plurality of my units I as herein described services a radio tube machine M, I have shown in Fig. 8 a schematic view arbitrarily indicated as of rotary table type, as such is characteristic and has its own peculiar difflculties.

The high vacuum suction of the units I may be connected with the vacuum system of the machine M as by manifolds I00 and suitable pipes IOI made as short stallation permits.

The present invention is the result in part of the above study and theorizing and has shown readings in the neighborhood of .01 micron, whereas in previous attempts at compounding, readings of .5 micron were considered good, but

and tight as the incould not be maintained consistently.

Following briefly the functioning of my present invention in an installation such as is schematically suggested in Fig. 8, the rarefied gases exhausted from the machine M through the connection I00 enter the high vacuum' stage through the suction connection 301: shown at the top of Fig. 2. This high vacuum stage is also shown on the left hand side of Fig. 1. From the gases pass through the .piston slide 1 being drawn into and forced out of the pump cylinder on which the baflie I00.is mounted.

9 bythe piston 0 at the discharge port 10 onthe right hand side of the cylinder bore. The gases and excess oil pass over the intermediate oil chamber I30, through the corridor P connecti to the suction side 2! of the, backing stage 20 (see Fig. 5). The pump, exhausts through the port 90, the exhaust matter passing about the condensing bafile I00 which tends to separate the oil and gases, the oil dropping into the reservoir I20 and the gases exhausting toatmosphere through the port 2011.. The oil chamber I20 is completely separated from the intermediate chamber I30 by the transverse wall Illa.

It will be noted that the discharge member of this backing stage is fitted with a spring loaded valve I40 (see Fig. 3) to prevent the reentrance of air and oil under atmospheric pressure. The discharge member 90 is shown in assembiy with the mushroom-shaped bafile I00 in Figs. 3 and 5. This member 90 is secured by suitable means to the pump wall above the cylinder 9 with its throat BI communicating with a pocket 92 in the pump wall'intowhich leads the exhaust port 9a from the pump cylinder 9 and 25 in which is positioned the 'valve I40.

At its outlet end the discharge member 90 flares outwardly and upwardly as at 90a, but itsv bottom portion is thickened and flattened as at 90 to provide a base for the vertical support 'IOI (Fig. 3). The baiile is also supported by brackets I02 suit-. ably secured to the discharge member adjacent either end thereof (Fig. 5).

As shown, the bailie I00 is of greater diameter than the width of the discharge member 90 so that the exhaust is substantially all delivered lee-- neath its concaved lower face, the oil impinging thereon falling back Into the reservoir I20 and the gases passing down and around the baffle and up and out through the outlet 20a.

As indicated above the clearances and parts in the high vacuum stage 3| are sealed and lubricated by the deaerated oil in the chamber I30 shown at the right of Fig. 2 through the small gear pump 6|, 62 shown at extreme left of Fig. 1 as controlled by the valve 69 the excess all being by-passed back to this same chamber.as at 68-48 shown in Fig. 6. The oil 0 in this chamber I30 is open to the suction intake of the" I backing up pump 20 through the corridor P and thus is continuously being deaerated.

The pump clearances and parts of backing stage 2| are similarly sealed and lubricated by atmospheric pressure on-the oil 0 instead of by a separate pump (see Fig. 7). The amount of oil delivered to the chamber '42 is controlled by the valve 81 in the passage 00 leading through the head 40 and communicating with the reservoir I20. (Figs. 7 and 9.) .Oil is also fed through the cap 80 shown in Fig. '7 to the stuffing box seal 8| shown in Fig. 1. This seal when properly lubricated without further adjustment effectively eliminates any leakage of air along the shaft and into the backing stage.

The above construction eliminates every possibility of leakage and allows the full pumpcapacity to be utilized in pumping down the system .to which it is attached, to those new'degrees of super vacua above indicated. It does this consistently in spite of machine fluctuations. In case of breakage of a tube under exhaustion in the machine. the positively fed oil seal of the high vacuum phase will hold against total loss of vacuum which in the operating machine necessitated a long delay to rebuild before prope evacuation could continue.

My invention is applicable through such units to all current types 01'- machines. The units are subject to modification within my invention by those skilled in this art.

What I, therefore claim and desire by Letters Patent to secure is:

l. A high vacuum pumping unit comprising a pairoi. separate rotary pumps, one of said pumps constituting a primary pump and the other of said pumps constituting a backing-up pump, each of said pumps including an intake port and a discharge port, said primary pump having a reservoir for sealing oil adjacent and connected to its discharge port and the discharge port of said primary pump opening into said reservoir above the level of the oil therein, the intake port of said backing-up pump being .operatively connected to said reservoir to continuously deaerate' the'sealing oil therein, and said connection be ervoir for deaerated oil, and said backing-up pump having a capacity relative to that of the primary pumpand to the space above the'oil in the reservoir such as to substantially immediately deaerate the oil in said reservoir.

3. A high vacuum pumping unit comprising a primary pump and a separate backing-up pump, each of said pumps including an intake port and a discharge port. said primary pump having a reservoir for sealing oil adjacent and connected to its discharge port and the discharge port of said primary pump opening into said reservoir above the level of the oil therein, the intake port 01'- said backing-up pump being operatively connected tosaid reservoir to continuously deaerate the sealing oil therein and said connection being at apoint belowthe discharge port 01' said primary pump so as to maintain the deaerated oil at a selected level, and means to continuously deliver a controlled flow of deaerated sealing oil to said primary pump from said reservoir a ainst the influence ot. the intake of said backing-up pump, said means comprising a' valvecontrolled delivery port in communication with said primary pump, a pump to supply deaerated oil from said reservoir to said delivery port, and

a pressure responsive by-psss connecting said delivery port and reservoir for returning excess deaerated oil lrom said delivery port to said reservoir..

4. A high vacuum pumping unit comprising a pair of separate rotary pumps, one of said pumps constituting a primary pump and the other of said pumps constitutin a ba p pump.

each oi said pumps including snintake' 1. a discharge port, and a reservoir for; sealing oil sdiacent and connected to its discharge port, the discharge port of said primary pump opening into its reservoir above the level of the oil therein, the intake port oi said backing-up pump being opersti'vely connected tothe reservoir of said primary pump to continuously the sealoil to said reservoir, and a pressure operable amazes ing oil therein, and said connection being at a point below the discharge port or the primary pump so as to maintain the deaerated oil at a selected level, mom to deliver sealing oil to said backing-up pump from its reservoir, and positive I pumping means to continuously deliver a controlled flow of deaerated sealing oil to said pri-.

--oil pump to said deaerated oil reservoir to return excess deaerated oil to said reservoir, and a pressure operable valve in said by-pass.

6. A high vacuum pumping unit comprising a casing and end walls, a pair of separate rotaryv pumps enclosed within said casing, one of said pumps constituting a primary pump and the other of said pumps constituting a backing-up pump, each of said pumps including an intake port, a discharge port and a reservoir for sealing oil adjacent and connected to its discharge port, the discharge port or said primary pump opening into its reservoir above the level of the oil therein, the intake port of said backing-up pump being operatively connected to the reservoir of said primary pump to continuously deaerate the sealing oil therein, said connection being at a point below the discharge port 01 the primary pump so as to maintain the deaerated oil at a selected level, means to deliver a controlled flow of sealing oil to said backing-up pump from its reservoir through said casing and one end wall, and positive pumping means to continuously deliver'a controlled flow of deaerated sealing oil through said casing and the other end wall to said primary pump from its reservoir against the influence of the intake 01' said backing-up-pump.

7. A high vacuum pumping unit comprising a casing and end walls, a pair ofseparate pumps enclosed within said casing, one of said pumps constituting a primary pump andthe other of said pumps constituting 'a backing-up pump, each of said pumps including an intake port 1 and a discharge port, said primary pump having a reservoir for sealing oil adjacent and connected to its discharge port. the discharge port otsaid primary pump opening into its reservoir above the level of the oil therein, the intake port of said backing-up pump being operatively connected to I said reservoir to continuously deaerate the sealing oil therein, said connection being at a point below the discharge port 0! the-primary pump so as to maintain the deaerated oil at a selected level, snd positive pumping means to continuously deliver a controlled new of deaerated sealthe influence or the intake or said backing-up pump.

s. The unit 01' claim-7, said means including a valve controlled conduittrom thedeaerated oil' reservoir to said primary pump, an oil pump in. said conduit. and a by-psss through said end wall and easing .irom'ssid oil pump to said deaerated oil reservoir to return excess deaerated valve in said by-psss.

9. A high vacuum pumping unitcomprisinga end-end wslls, a pair oi separate rotary pumps in'ssid casing, a u

pumps from each other, one of said pumps constituting a primary pump and the other of said pumps constituting a backing-up pump, each of said pumps including an intake port, a discharge port, and a reservoir for sealing oil adjacent and connected to its discharge port, said partition having a passage therethrough to connect the intake port of said backing-up pump to the space above the level of the oil in the said primary pump reservoir so that said backing-up pump continuously deaerates sealing oil in said reservoir, a common shaft for said pumps extending through said partition and end walls sealing means for said shaft located in the end wall adjacent said backing-up pump, a bearing carried in each of said end walls to support said shaft, means to deliver sealing oil from said reservoir of said backing-up pump through said casing and the end ,wall adjacent said backingup pump to one bearing and along said shaft to said backing-up pump and to said shaft sealing means, and positive pumping means to continuously deliver a regulated flow of deaerated sealing oil from. said reservoir for said primary pump through said casing and the other end wall to the other bearing and along said shaft to said primary pump against the influence of said backing-up pump. v

10. A high vacuum pumping unit comprising a casing and end walls, a pair of separate rotary pumps in said casing, a partition separating said pumps from each other, one of said pumps constituting a primary pump and the other of said pumps constituting a backing-up pump, each of said pumps including 'an intake port, a discharge port, and a reservoir for sealing oil adjacent and connected to its discharge port, the intake port of said backing-up pump being operativelyconnected to the space above the level of the oil in the reservoir of said primary pump so that said backing-up pump continuously deaerates the sealing oil therein, a common shaft for said pumps extending through said partition and end walls, a bearing carried in each of said end walls -to support said shaft, a head secured to each end wall, the head secured to the end wall adjacent said backing-up pump including a chamber having an aperture to receive said shaft, sealing means for said shaft in said chamber compressibly interposed between said head and said end wall, means to deliver sealing oil from said reservoir for said backing-up pump through said casing and the end wall adiacent said backing-up pump to one bearing and along said shaft to said backing-up pump and through said head to said compressible sealing means, and positive pumping means to continuously deliver a regulated flow of deaerated sealing oil' from said reservoir for said primary pump through said casing, the other end wall and head to the other bearing and along said shaft to said primary pump against the influence of the backingup pump.

11. A high vacuum pumping unit comprising a casing and first and second end walls including first and second end plates and heads, a pair of separate rotary pumps in said casing, a partition separating said pumps from each other, one of said pumps constituting a primary pump and the other of said pumps constituting a backingup pump, each of said pumps including an intake port, a discharge port, and a reservoir for sealing oil adjacent and connected to its discharge port, the intake port of said backingmp pump being operatively connected to the space above the level of the oil in the reservoir of said primary pump so that said backing-up pump continuously deaerates the sealingoil therein, a common shaft for said pumps, said end plates, said partition and said second head being apertured to receive said shaft, bearings carried by said end plates to support said shaft, resilient shaft sealing means between said second head and second end plate, a conduit from said reservoir for said backing-up pump extending through said casing, said second end plate and said second head in communication with said shaft sealing means, a branch conduit through said second end plate in communication with said flrstnamed conduit and the bearing in said second end plate and a valve in said second conduit to regulate the flow of oil to said second end plate bearing, an oil pump having an intake port and adischarge port, means intermediate the first end plate :and the-flrsthead carrying said oil pump and connecting it to said shaft, aconduit from said reservoir for deaerated oil through said casing, said first end plate, and said first head in communication with said intake port of said oil pump, a conduit from said discharge port of said oil pump in communication with the bearend plate and said casing to return excess;

deaerated oil to itsreservoir, and a operable valve in said by-pass.

. HAROLD I, STOL'IZ.

pressure 

